Ok, this is technically not wrong, but it's also completely insane. They key part of this calculation is that it assumes humanities energy consumption will keep on growing at 2% for the next thousand years. At that point (assuming it is ever reached), humanities yearly energy expenditure would be approx 10^28 Joules per year, which pretty close to the output of a small star (the sun outputs about 10^26 Joules per second (per google), and it is not that small). If we're all still living on earth at that point, slowing down the rotation of the earth would be the least of our problems.